Several different cutaneous and deep somatic (intramuscular) laboratory pain-induction methods will be compared and evaluated for their applicability as objective, reliable and valid pain measurement instruments, and two or three of them selected as the most valid and practical (i.e. simple and fast) components of a pain "thermometer" or algesiometer. Chemical, thermal, electrical and mechanical noxious stimuli will be studied. Each method will yield four pain response parameters, namely pain threshold, drug request point, pain tolerance, and pain sensitivity range. Using paid, healthy normal subjects, the data will be correlated within and between techniques and response parameters to yield a correlation matrix. This matrix will be subjected to factor analysis in order to isolate a specific pain factor, termed pain endurance. It is hoped that this specific factor will greatly assist in the development of the pain measurement battery. Various of the above pain-induction methods will be studied under double-blind conditions with several analgesic drugs, such as codeine, propoxyphene and aspirin, and other treatments for pain relief, such as transcutaneous electrical stimulation, in order to validate the pain measurement battery. The advantage of complete cross-over designs to single dose designs in drug studies with healthy normal volunteers will be examined to determine future experimental approaches.